What Is An EPROM? Unlocking The Discontinued Memory Device!

A ROM or Read-Only Memory device is crucial to start up any computing device. Since a ROM contains start-up codes, no computer or laptop can manage to operate without it.

what is an eprom
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The fleet of ROM devices consists of three types namely PROM, EPROM, and EEPROM.

Skipping PROM which has been covered in the previous post, It’s time to move to EPROM for a new lesson. Today’s post includes programming mechanisms, characteristics, and uses of EPROM.

What Is An EPROM?

EPROM or Erasable Programmable Read-Only Memory was a non-volatile memory device used for storing small amounts of data. Primarily, it was designed to be used in general-purpose computers.

Introduced by Dov Frohman of Intel in 1971, EPROM offered a set of advantages over the conventionally used PROM. Right after the introduction, EPROM gained superiority over PROM simply because it could be erased and reprogrammed multiple times.

The erasure and reprogramming process required a significant amount of effort from the ends of a data eraser and a reprogrammer. In other words, It was no easy game to erase or reprogram an EPROM.

Disappeared from the market ages ago, EPROMs have been replaced by EEPROMs as successors. Today, EPROMs are classified as legacy technology in the domain of computer memory

How Is An EPROM Programmed?

An EPROM consisted of multiple floating gate transistors attached to each other. These transistors held key importance in the overall structure of an EPROM.

In order to reprogram an EPROM, the programmer had to program every transistor individually using an electric device. Powered by high voltages, the electric device had to target every single floating gate transistor in a detailed manner.

The above-mentioned process allowed the programmer to preserve the data in the EPROM while keeping it safe for more cycles of reprogramming.

Characteristics Of EPROM

EPROMs offered a great package of characteristics to the PC manufacturers. They were adopted by the PC community for their impressive data storing capabilities. Without wasting much of your precious time, the following are the major characteristics of EPROMs.

Long-Term Data Retention

Believe it or not but EPROMs had a super good memory. They could remember the programs installed in them even after decades. According to the manufacturers, EPROMs could hold the data for as long as at least 10 years. However, as per the highest estimate, EPROMs could retain data for more than 20 years. Unsure about you folks but two decades are quite a long period of time for me.


As discussed earlier, EPROMs could be reprogrammed multiple times. Their reprogramming capability was a revolution in the world of Read-Only Memory. Thankfully, EPROMs were not like stubborn PROMs that would never be reprogrammed. Instead, they were the advanced versions of ROM with enough flexibility to be erased and reprogrammed.

Transparent Window

The external structure of an EPROM featured a transparent window made of fused quartz. This was an abnormal structure considering the fact that PROM came with a metalloid structure with nothing on top of it. Despite the abnormality, it looked futuristic and beyond good.

However, this wasn’t what the window was there for. It was there to make the chip visible so that it could be exposed to ultraviolet light during erasing.


The commercial success of a product is largely determined by its cost-effectiveness. If the element of cost-effectiveness is absent in a product, it is bound to fail.

Making a comparison, there is no doubt EPROMs were costlier than the much older PROMs. But it is noteworthy that they offered greater performance than the latter. The improved performance of an EPROM outweighed its increased prices making it a cost-effective product.


The use of Erasable Programmable Read-Only Memory included several types of electronic devices. Firstly, EPROMs were applied to general-purpose computers.

They operated alongside RAMs as the primary non-volatile memory in computers. After the successful commercial inclusion in computer systems, EPROMs were added to more and more electronic devices.

In addition to the electronic products, they were also used in many other types of devices. With a very small form factor, It was quite easy to add EPROMs into small devices. Thus, they were used in a range of lightweight devices.

For example, EPROMs were integrated into smart cards on a large scale. Moreover, remote keyless systems also adopted these memory devices.

Frequently Asked Questions

Wrap Up

EPROM memory modules were far ahead of the PROMs. Whether it was the data access time or reprogramming, EPROMs used to be better than the latter. The discontinuation of EPROM only hints at its undeniable success that forced the ROM manufacturers to come up with EEPROM. The most advanced type of ROM, EEPROM is the successive technology to EPROM.

I would want to conclude the post with the fact EPROMs were a success for the ROM manufacturers. These memory modules are the reason EEPROMs were developed and introduced commercially. Stopping here, I will target EEPROMs in my next post to wrap up the ROM series. If you liked this post or have anything to share about EPROMs, please do let me know in the comment section.

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Bilal Khan
Bilal Khan

Bilal might look like a Bearded Caucasian right out of a Viking movie but trust me he's a native Pakistani. He has a long list of hobbies among which staying updated on the Latest Technology and Hardware happens to be on the top. If you are looking for detailed hardware explanations through no tricky terminologies, follow him to read Tech Content curated perfectly for the human brain.

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